<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="UTF-8" />
    <meta http-equiv="X-UA-Compatible" content="IE=edge" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <title>Document</title>
    <script src="../react18/react.development.js"></script>
    <script src="../react18/react-dom.development.js"></script>
    <script src="../react18/babel.min.js"></script>
  </head>
  <body>
    <button id="btn">按钮</button>
    <div id="app"></div>
    <script type="text/babel">
      const oBtn = document.getElementById("btn");

      //得到一个初始的列表数据
      const userData = ["HTML", "CSS", "JavaScript", "NodeJS"];

      //根据数据 列表渲染
      const vDom = (
        <ul>
          {userData.map((item) => {
            return <li>{item}</li>;
          })}
        </ul>
      );

      //渲染
      const root = ReactDOM.createRoot(document.getElementById("app"));
      root.render(vDom);

      //点击按钮改变数据重新渲染
      oBtn.onclick = function () {
        userData.unshift("React");

        //重新得到虚拟DOM,然后渲染
        const vDom = (
          <ul>
            {userData.map((item) => {
              return <li>{item}</li>;
            })}
          </ul>
        );

        root.render(vDom);
        
      };
    </script>
  </body>
</html>
